Level control attachment for road graders



9 O A-. GURRIES E l'AL 2,870,555

LEVEL CONTROL ATTACHMENT FOR ROAD GRADERS Filed Nov. 50, 1956 2 Sheets-Sheet 1,.

INV EN TORS RA. Gurries BY John CuJ'ZeZZ Jan. 27, 1959 R. A. GURRIES ET AL 2,870,555

LEVEL CONTROL ATTACHMENT FOR ROAD GRADERS Filed Nov. 30, 1956 2 Sheets-Sheet 2 m Wm n mnm U E 1 47 V a K .p. Z w/ HA v 2 y B 2 2 8 5 3// 3 x O a v o M O 2 a .M. 3 3

United States Patent M 2,870,555 IJE'VEL CONTROL ATTACHMENT FOR ROAD GRADERS Raymond A. Gurries, San Jose, and- John Curle'tt, Los Gatos, (Salifi, assignors to Gurries Manufacturing Co., San Jose, Calif., a corporation-of California Application November 30, 1956, Serial No. 625,527

Claims. (Cl. 37 180) This invention relates toroad graders whose wheel 'base is limited in order toallowturnin'g of the machines in narrow road beds, and which short wheel base also .limits the finishing accuracy of the grading operations.

The principal object of the invention is to provide an attachment whereby level of the blade in a conventional grader is automatically held in relation to an extended wheel base.

Another major object of this invention is to provide a device-in the form of an attachment for a graderwhereby not only is the level of the blade'automatically controlled, but the effective wheel base of the grader "is practically doubled, enabling a much more sensitive :and accurate level control to'be had than is now the case; By means of this device, therefore, the finished grade may be held withinvery close limits, and without any attention on the part of the operator of the grader.

The device includes an elongated boo'm projecting ahead of the machine and provided at its forward end with a ground engaging feeler wheel; the boom being mounted for vertical swinging movement, and the swinging of which-as occasioned by vertical movement of the feeler wheel-determines and controls the relative vertical movement of the grader blade. This feelerwheel thus replaces the front wheels of the grader in establishing the plane of operation of the grader blade.

A further object of the invention therefore is to mount the boom on the grader so that when the use of the boom is not desired, as when the machine is doing rough rather than finish grading, the boom may be retracted or shifted rearwardly on the machine to an inoperative position and with the feeler Wheel then clear of the ground. The grader blade may then be controlled by the operator of the machine in the usual manner, and the elongated boombeing retracteddoes' not interfere with turning of the machine through a relatively small radius, as is necessary under certain conditions of operation or'transportation. At the same time, the boom remains on the machine so that it can be shifted to an operative position whenever desired.

Another object of the invention is to provide a device for the purpose in the form of an attachment which may be applied to a conventional or standard grader, with but few changes having to be made to the grader other than a remodeling of the front wheel truck of the grader.

Still another object of the invention is to provide a practical, reliable, and durable level control attachment for road graders, and one which will be exceedingly effective for the purpose for which it is designed.

These objects are accomplished by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claims.

In the drawings:

Fig. 1 is a diagrammatic outline of a grader, showing the level control attachment mounted thereon and with the. boom of the attachment in its operative position.

2,870,555 Patented Jan. 27, 1959 Fig.- Z'is av similar View, but. shows the boom. retracted to an inoperative: position.

Fig. 3 is'an enlarged longitudinal section ofthe boom mounting; sleeve, together with a portion of the boom and the" boom-shifting: mechanism.

Fig.4 is a transverse section on line 4- -4 of Fig. 3.

Fig. 5 is a'similari view on line 5-5 of Fig. 3.

Referring now moreparticularly to the drawings, and to the characters of: reference marked thereon, the graderindicated generally at1-include's an elongated arched frame 2 supported at its rear end by a driven wh'eel truck '3, and afthefrorit' end by a steerable wheel truck 4 which includes a central standard 5 which contains the steering mechanism for the wheels of said truck; the steering bein effected in the-usual manner and controlled by suitablemeans (not shown) operable by the driver of the grader from his seat or station 6 thereon.

The: grader also includes an auxiliary frame 7 projecting rearwardly fromand swivelly connected to--the forward e'nd'of the frame 2, and at its rear end supporting a grader blade 8in the usual manner. While this blade may be manually adjusted vertically relative to the frame, it is no'rmally'maintained rigid therewith by the connecting links between the frames 2 and 7, and one of which links is indicated at 9.

Ordinarily, the standard 5 (or its equivalent) is rigid with frame 2. However, in order to apply our improved level control means to the grader, the standard 5 is separated from the frame 2', and is connected thereto by upper and lower parallell inks 10 and 11, respectively. The rear cross shaft 12 of the upper links' 10 isfrigid with said links and with an upstanding arm 13, which-at its upper end*i's connected to the piston rod 14 of a one-way hydraulic cylinder 15 which, at its rear end, is'swivelly supportedas at 16'from the frame 2.

By reason of this construction it will be seen that if the piston rod advances, the frame 2 will be raised relative to the ground and the front wheel truck, and the blade 8 will be likewise raised. Conversely, if the pressure holding the piston rod advanced is released, the frame 2 and the blade will drop of their own weight relative to the ground and the front wheel truck.

This control of the hydraulic cylinder is effected-as the grader moves along the ground-by the following means:

A hanger sleeve 17 is disposed above the frame 2 adjacent its forward end, the sleeve being formed with cent'rally located side trunnions 18 turnable in bearing brackets '19 mounted on and upstanding from the frame 2. An elongated boom 20 is slidable through the sleeve, being engaged in guiding relation by a top roller 21 mounted in the sleeve centrally of its length, and by diagonally disposed side bottom rollers 22 mounted on the sleeve adjacent the ends thereof.

At its rear end the boom is formed with a stop 23 which prevents forward movement of the boom out of the sleeve, and at its forward end the boo-m is provided with a feeler in the form of a caster wheel 24 to engage the ground. An arm 25 is rigid with, and upstands from, the sleeve adjacent its rear end and is connected by a link 26 with the plunger 27 of a valve 28 of a sensitive closedcen'te'r piston type, which is mounted in a fixed position on the frame 2'. The valve is provided with a normally closed feed and relief conduit 29 leading to the rear end of the cylinder 15, and with pressure-feed and-relief con duits 30 and 31, respectively. These conduits are of course connected in a hydraulic pressure systemof conventional form, and'which is mounted on the grader.

Conduits 30 and 31, together with conduit 29, are arranged relative to each other and to the plunger so that when the plunger is advanced, communication is estab- 3 lished between conduits 29 and 31 to relieve the pressure from the cylinder to thus allow the frame 2 and blade 8 to drop. When the plunger is retracted from such normally closed position, communication is established between conduits 29 and 30, causing fluid under pressure to be fed to the cylinder 15 and the frame 2 to be raised.

Since these movements of the plunger are caused by the swinging of the sleeve due to swinging of the extended boom as the wheel 24 rides over rises or depressions in the ground, the level of the blade 8 is correspondingly altered. In other words, any movements of the boom are transmitted into corresponding movements of the grader frame so as to cause the frame to assume the same angular relationship to the boom as at the start; the valve plunger then of course returning to its normal closed position. The blade of the relatively short wheel base grader is therefore accurately controlled in its level as effectively as if the wheel base was substantially twice as long.

The boom when in operative position is fully extended from the hanger sleeve, and to retain the boom in such relationship to the sleeve, while enabling the boom to be easily retracted through the sleeve when desired, the following arrangement is provided:

A pinion sprocket or gear 32 is disposed within the sleeve 17. being mounted on an axial shaft 33 journaled in the trunnions 18. The sprocket engages a rack 34 secured on and extending along the underside of the boom; this rack, for cheapness of construction without sacrifice of efficiency, being preferably a length of conventional driving chain, as shown.

The shaft 33 projects at one end beyond one of the trunnions, and at said end a sprocket 35 is mounted thereon. This sprocket is connected by a chain 36 with a pinion sprocket 37 mounted on, and driven by, a motor 38 of any suitable character, and which motor is fixed on the grader frame 2.

When the boom is fully retracted, upon operation of motor 38, the rear end thereof is received in a side cradle 39 supported from a standard 40 mounted on the grader near its rear end. The cradle is disposed at a height, and

at an angle to the horizontal, such that the boom is retained in practically the same angular relation to the frame 2 as when the boom is extended with the wheel 24 in ground engagement.

The valve 15 is therefore not affected by the retraction of the boom and is held in a closed position so that the front wheel truck 4 and the grader frame are retained in rigid relationship with each other as far as downward movement of the frame 2 relative to the wheel truck 4 is concerned, and the grader blade may then be controlled in the customary manner.

Also, the length of the grader, when the boom is retracted, is not appreciably increased, so that the grader may be turned in narrow road beds, and otherwise easily manipulated around sharp curves and in relatively confined quarters.

From the foregoing description it will be readily seen that there has been produced such a device as will substantially fulfill the objects of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claims.

Having thus described the invention, the following is claimed as new and useful, and upon which Letters Patent are desired:

1. A grade control device for the blade of a road grader, said grader comprising a rigid frame, wheels supporting the frame at its rear end, a grading blade rigid with the frame intermediate its end, and a front wheel truck; the device comprising longitudinally extending vertically spaced links connecting the wheel truck and frame for vertical movement of the front end of the frame relative to the truck; a forwardly extending boom having a feeler at its forward end to engage the ground a material distance ahead of the front wheel truck, boom mounting means including a sleeve slidably supporting the boom adjacent its normally rear end, means mounting the sleeve on the grader frame for swinging about a transverse axis, the boom being relatively rigid with the sleeve whereby to swing therewith as a unit, and a mechanism connected between the sleeve and one of the parallel links to relatively swing the latter up and down so as to raise and lower the grader frame upon corresponding vertical movement of the feeler and the resulting swinging of the boom and sleeve.

2. A grade control device for the blade of a road grader, said grader comprising a rigid frame, Wheels supporting the frame at its rear end, a grading blade rigid with the frame intermediate its ends, and a front wheel truck; the device comprising means connecting the truck to the front end of the grader frame for relative vertical movement of the frame at said end, a forwardly projecting boom having a feeler at its forward end to engage the ground a material distance ahead of the front wheel truck, means mounting the boom on the grader for vertical swinging movement, and a mechanism connected to the boom mounting means and the truck connecting means to impart relative vertical movement to the grader frame upon corresponding vertical movement of the feeler and the resulting swinging of the boom; the boom mounting means including a sleeve through which the boom is slidable, trunnions fixed on the sides of the sleeve, bearing brackets on the grader frame in which the trunnions are turnable, a pinion in the sleeve in vertically spaced relation to the boom, a rack on the boom engaged by the pinion, and an optionally driven shaft fixed with the pinion and turnable in the trunnions.

3. A device, as in claim 2, with rollers mounted in the sleeve to the sides of the rack and adjacent both ends of the sleeve and engaging the boom in supporting relation.

4. A grade control device for the blade of a road grader, said grader comprising a rigid frame, wheels supporting the frame at its rear end, a grading blade rigid with the frame intermediate its ends, and a front wheel truck; the device comprising means connecting the truck to the front end of the grader frame for relative vertical movement of the frame at said end, a normally inactive power mechanism on the grader frame connected to the truck connecting means to impart such movement to the frame, said mechanism including a normally closed valve having an actuating element projecting therefrom, a forwardly projecting boom having a ground engaging feeler at its forward end, a sleeve pivoted on the grader frame through which the boom projects in slidably guided relation, means to slide the boom and to maintain the boom in any slid position relative to the sleeve, an arm rigid with and projecting upwardly from the sleeve, and a push-pull connection member between the arm and the valve actuating element.

References Cited in the file of this patent UNITED STATES PATENTS 1,762,441 Johnson June 10, 1930 2,464,227 Gurries et a1. Mar. 15, 1949 2,787,066 Johnson Apr. 2, 1957 2,792,651 Hobday May 21, 1957 

